linux/fs/verity/hash_algs.c

// SPDX-License-Identifier: GPL-2.0
/*
 * fs-verity hash algorithms
 *
 * Copyright 2019 Google LLC
 */

#include "fsverity_private.h"

#include <crypto/hash.h>

/* The hash algorithms supported by fs-verity */
struct fsverity_hash_alg fsverity_hash_algs[] = …;

static DEFINE_MUTEX(fsverity_hash_alg_init_mutex);

/**
 * fsverity_get_hash_alg() - validate and prepare a hash algorithm
 * @inode: optional inode for logging purposes
 * @num: the hash algorithm number
 *
 * Get the struct fsverity_hash_alg for the given hash algorithm number, and
 * ensure it has a hash transform ready to go.  The hash transforms are
 * allocated on-demand so that we don't waste resources unnecessarily, and
 * because the crypto modules may be initialized later than fs/verity/.
 *
 * Return: pointer to the hash alg on success, else an ERR_PTR()
 */
const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,
						      unsigned int num)
{ … }

/**
 * fsverity_prepare_hash_state() - precompute the initial hash state
 * @alg: hash algorithm
 * @salt: a salt which is to be prepended to all data to be hashed
 * @salt_size: salt size in bytes, possibly 0
 *
 * Return: NULL if the salt is empty, otherwise the kmalloc()'ed precomputed
 *	   initial hash state on success or an ERR_PTR() on failure.
 */
const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg,
				      const u8 *salt, size_t salt_size)
{ … }

/**
 * fsverity_hash_block() - hash a single data or hash block
 * @params: the Merkle tree's parameters
 * @inode: inode for which the hashing is being done
 * @data: virtual address of a buffer containing the block to hash
 * @out: output digest, size 'params->digest_size' bytes
 *
 * Hash a single data or hash block.  The hash is salted if a salt is specified
 * in the Merkle tree parameters.
 *
 * Return: 0 on success, -errno on failure
 */
int fsverity_hash_block(const struct merkle_tree_params *params,
			const struct inode *inode, const void *data, u8 *out)
{ … }

/**
 * fsverity_hash_buffer() - hash some data
 * @alg: the hash algorithm to use
 * @data: the data to hash
 * @size: size of data to hash, in bytes
 * @out: output digest, size 'alg->digest_size' bytes
 *
 * Return: 0 on success, -errno on failure
 */
int fsverity_hash_buffer(const struct fsverity_hash_alg *alg,
			 const void *data, size_t size, u8 *out)
{ … }

void __init fsverity_check_hash_algs(void)
{ … }